docstr: Tests the `fill` argument of `get` with a lookback range >0.
docstr_tok: ["Tests","the","`","fill","`","argument","of","`","get","`","with","a","lookback","range",">","0","."]
code: def test_get_with_lookback_and_fill(self):
      """Tests the `fill` argument of `get` with a lookback range >0."""
      buffer = BufferWithInfiniteLookback(
          data=[0, 1, 2, 3, 4, 5],
          lookback=3,
          # Specify a space, so we can fill and one-hot discrete data properly.
          space=gym.spaces.Discrete(6),
      )
  
      # Test on ongoing and finalized buffer.
      for finalized in [False, True]:
          if finalized:
              buffer.finalize()
  
          self.assertTrue(len(buffer), 3)
  
          # Individual indices with fill.
          check(buffer.get(-10, fill=10), 10)
          check(buffer.get(-3, fill=10), 3)
          check(buffer.get(-2, fill=10), 4)
          check(buffer.get(-1, fill=10), 5)
          check(buffer.get(0, fill=10), 3)
          check(buffer.get(2, fill=10), 5)
          check(buffer.get(100, fill=10), 10)
  
          # Left fill.
          check(
              buffer.get(slice(-8, None), fill=10),
              [10, 10, 0, 1, 2, 3, 4, 5],
          )
          check(
              buffer.get(slice(-9, None), fill=10),
              [10, 10, 10, 0, 1, 2, 3, 4, 5],
          )
          check(
              buffer.get(slice(-10, None), fill=11),
              [11, 11, 11, 11, 0, 1, 2, 3, 4, 5],
          )
          check(
              buffer.get(slice(-10, -4), fill=11),
              [11, 11, 11, 11, 0, 1],
          )
          # Both start stop on left side.
          check(buffer.get(slice(-10, -9), fill=0), [0])
          check(buffer.get(slice(-20, -15), fill=0), [0, 0, 0, 0, 0])
          check(buffer.get(slice(-1001, -1000), fill=6), [6])
          # Both start stop on right side.
          check(buffer.get(slice(10, 15), fill=0), [0, 0, 0, 0, 0])
          check(buffer.get(slice(15, 17), fill=0), [0, 0])
          check(buffer.get(slice(1000, 1001), fill=6), [6])
          # Right fill.
          check(
              buffer.get(slice(2, 8), fill=12), [5, 12, 12, 12, 12, 12]
          )
          check(
              buffer.get(slice(1, 7), fill=13), [4, 5, 13, 13, 13, 13]
          )
          check(buffer.get(slice(1, 5), fill=-14), [4, 5, -14, -14])
          # No fill necessary (even though requested).
          check(buffer.get(slice(-5, None), fill=999), [1, 2, 3, 4, 5])
          check(buffer.get(slice(-6, -1), fill=999), [0, 1, 2, 3, 4])
          check(buffer.get(slice(0, 2), fill=999), [3, 4])
          check(buffer.get(slice(1, None), fill=999), [4, 5])
          check(buffer.get(slice(None, 3), fill=999), [3, 4, 5])
  
      # Check the type on the finalized buffer (numpy arrays).
      data = buffer.get(slice(15, 17), fill=0)
      self.assertTrue(isinstance(data, np.ndarray))
      check(data, [0, 0])
  
file_path: ray/rllib/env/tests/test_lookback_buffer.py
imports: import unittest
  import gymnasium
  import numpy
  from ray.rllib.env.utils import BufferWithInfiniteLookback
  from ray.rllib.utils.spaces.space_utils import batch, get_dummy_batch_for_space
  from ray.rllib.utils.test_utils import check
label_desc: Use image node_id 5 for calling the TestBufferWithInfiniteLookback obj's underlying member method code with example usage: obj.test_get_with_lookback_and_fill() without return types